Apparatus and method for moulding an opening device on a packaging sheet

ABSTRACT

An apparatus and method for moulding opening devices onto a packaging material sheet at respective holes provided in the sheet includes first and second mould tools arrangeable in a closed position so as to be in contact with opposite sides of the sheet and in an open position so as to be positioned distally from the sheet. In the closed positions a mould cavity is formed between the first and second mould tools for accommodating a hole edge in the sheet. One of the mould tools includes a pair of half mould tools which are simultaneously moved from the open position to the closed position and vice versa such that the direction of movement of each of said half mould tools between the open and closed positions have a directional component extending substantially parallel to the extension plane and a directional component extending substantially perpendicularly to the extension plane, for reducing wear of the mould tools.

This application is a continuation of U.S. patent application Ser. No.09/269,507, filed Mar. 29, 1999, now U.S. Pat. No. 6,303,066, which is anational stage application under 35 U.S.C. § 371 of Internationalapplication PCT/SE97/01594, filed Sep. 23, 1997, which Internationalapplication was published in English and designated the United States,and which International application claims priority to Italian patentapplication MI96A002272, filed Oct. 31, 1996.

TECHNICAL FIELD

The present invention relates to an apparatus and a method for directinjection moulding of a plastics material opening device to a holeprovided on a sheet of packaging material. The term “opening device” asused herein, refers mainly to opening devices used for pouring liquidcontents from a container, but also includes opening devices which maybe used for filling a container.

BACKGROUND ART

Opening devices of different types provided on a packaging containerformed by packaging sheet material and adapted for containing substancessuch as foodstuffs, and in particular for containing liquid beveragessuch as juices, water, milk, wine, etc. are known.

One such opening device includes a perforation on a wall part of thepackaging container and a plastics material lid device attached to thewall part and covering the perforation in a closed state. The lid deviceincludes a circumferential base attached to the wall part, for exampleby means of adhesives, circumferentially surrounding the perforation,and a lid element hinged to the base. Once the lid element is opened,the perforation may be engaged and forced open so that the contentsinside the packaging container may be dispensed therefrom.

Another known opening device includes an opening provided on a wall partof the packaging container and a plastics material lid device similar tothe one described above attached to the wall part and covering theopening in a closed state. A sealing element such as an aluminium pulltab is connected to the wall part so as to cover the opening, and oncethe lid element has been opened, the sealing element may be removed toexpose the opening for dispensing the contents of the packagingcontainer.

Methods for providing the above opening devices on the packagingcontainers may include feeding a continuous web of packaging material toa first station at which the perforation or opening is provided on theweb, and to a second station at which the lid element is attached to theweb for covering the perforation or opening. The aluminium pull tab, ifprovided i.e. for covering the opening, is attached in an intermediatestep. After the opening devices are provided on the web, packagingcontainers from the web are formed, filled with product, and sealed,such that the opening devices are arranged on the finished containerpackagings for easy access.

One example of a machine for forming, filling, and sealing packagingcontainers is the TB8 filling machine, manufactured by Tetra BrikPackaging Systems of Modena, Italy.

As an alternative to the above opening devices, in which an alreadyformed plastics material lid device is applied to the sheet, U.S. Pat.No. 4,725,213 (the disclosure of which is incorporated herein byreference) discloses a plastics material opening device which isinjection moulded directly onto the sheet of packaging material. Inparticular, a pair of mould tools are moved into arrangement about aprestamped hole in the sheet, and heated thermoplastics material isinjected through an injection passage defined between one of the mouldtools and one surface of the sheet and extending along such surface ofthe sheet in order to form the opening device at the prestamped hole.

Although the method and apparatus for providing this latter type ofopening device may be completely valid, there exists in the field ofthermoplastics material injected opening devices the need for furtherimprovements.

The injection passage in U.S. Pat. No. 4,725,213 extends from theinjector head for a significant distance along one surface of the sheetto one end of the mould cavity for forming the opening device, so as tocreate a number of disadvantageous effects. Since the injection passageenters the mould cavity at one end, the complete filling of the mouldcavity with heated thermoplastics material is rendered difficult andinefficient particularly at the portion of the mould cavity arrangeddistally from the injection passage. Moreover, if the injection passageextending along one surface of the sheet is excessively long, thefilling of the mould cavity is rendered even more difficult andinefficient, and therefore the apparatus and method are limited tomoulding opening devices arranged substantially only near the edge ofthe sheet at which the injection head is positioned. Additionally, astrip of plastics material is formed in the injection passage, andfurther steps must be made to eliminate such strip, which isadditionally inefficient and which creates the possibility of damagingthe opening device from which such strip must be removed. Furthercomplications arise from subjecting the surface of the sheet ofpackaging material, which generally has a very low stiffness andresistance, to thermoplastics material at elevated pressures andtemperatures injected into the injection passage.

The above described difficulties in completely filling the mould cavitymay lead to a situation in which plastics material will not flow to allparts of the mould cavity and as a result, the edge of the opening maynot be sufficiently to sealed by plastics material of the openingdevice. Generally, the packaging sheet material is formed of severallayers including an inner paper layer and two outer synthetic plasticsmaterial coating layers, one of which is destined to form a productcontact surface. Other possible layers such as printing ink layers,laminating layers and aluminium foil layers may be interposed betweenthe paper layer and the outer coating layers. When the opening in thepackaging sheet material is stamped, the internal layers of thepackaging sheet are exposed at the edge of the opening, and unless suchedge is adequately sealed by the injected thermoplastics materialopening device, the packaged product may come into contact with theinternal layers of the packaging sheet material possibly causing damagethereto. Moreover, the overall efficiency of the apparatus and method iscompromised when the time needed to inject the heated thermoplasticsmaterial for each mould operation is increased so as to assure anadequate filling of the mould cavity.

The mould tools in U.S. Pat. No. 4,725,213 consist of a pair of mouldtools which are both movable in opening and closing directions whichextend perpendicularly to the extension of the sheet. Such aconfiguration substantially limits the flexibility of the device informing opening devices with different shapes, since the mould toolsmust not encounter any portions of the opening device which protrude ina direction perpendicular to the direction of movement of the mouldtools. The injection moulded opening device of U.S. Pat. No. 4,725,213indeed includes a pull tab which extends in a direction perpendicular tothe sheet, for a long extension sufficient to be gripped by a user. Suchan extensively protruding pull tab is disadvantageous with regard tostoring and shipping packaging containers including an opening device ofthis type.

It is furthermore desirous to have opening devices with base portionsconnected to the sheet hole and lid portions positioned in planes whichare slightly raised with respect to the base portions and the packagingsheet. These lid portions have an edge or lip which extends parallel tothe extension of the packaging sheet, so that they may be gripped andopened by a user. The apparatus of U.S. Pat. No. 4,725,213 is incapableof forming opening devices of this type due to the opening movement ofthe mould tools.

What is needed is an apparatus and method for injection moulding athermoplastics material opening device onto a packaging material sheetwhich allows to assure that the opening device is moulded in a mosteffective and efficient manner possible.

DISCLOSURE OF THE INVENTION

In accordance with one preferred aspect of the invention, there isprovided in a packaging machine for forming package containers from adriven web of packaging sheet material, an opening device mouldingstation for moulding opening devices on to the web at respective holesprovided in the web, which opening device moulding station includesfirst and second mould tools releasably arrangeable in closed positionsso as to form a mould cavity for accommodating the hole edge of the web.An injection passage for injecting heated thermoplastics material intothe mould cavity extends in at least one of the first and second mouldtools such that the thermoplastics material is injected directly intothe mould cavity at an injection point of the mould cavity which islocated distally from the hole edge.

By having the injection point arranged distally from the hole edge, theheated thermoplastics material advantageously enters the mould cavity ata position which permits the filling of the mould cavity to be carriedout in an effective and efficient manner. The heated plastics materialwill flow from the injection point smoothly and evenly initiallydistally from the hole edge and successively fill the mould cavity sothat the heated plastics material makes contact with the hole edge atthe end of the injection step. The times required for each injectionstep are therefore minimised in order to increase the efficiency of theopening device moulding operation.

According to a most preferred aspect of the invention, the injectionpoint is arranged at a lid forming portion of the mould cavity, in asubstantially central position with respect to a base forming portion ofthe mould cavity, and the injection passage extends in one of the mouldtools in a direction which is substantially perpendicular to theextension of the lid forming portion of the mould cavity. Such aconfiguration allows to fully maximise the efficiency of material flowfrom the injection point in a symmetrical and even manner initiallydistally from the hole edge and successively to fill the base formingportion of the mould cavity. Such configuration also allows to fullyavoid subjecting surfaces of the web to the flow of heatedthermoplastics material.

In accordance with another preferred aspect of the invention, there isprovided an opening device moulding apparatus for moulding plasticsmaterial opening devices on to a sheet at respective holes provided inthe sheet, which opening device moulding apparatus includes first andsecond mould tools releasably arrangeable in closed positions so as toform a mould cavity for accommodating the hole edge of the sheet, adrive mechanism for selectively moving the first mould tool and saidsecond mould tool between the open and closed positions, and at leastone of the first and second mould tools includes a pair of half mouldtools. The drive mechanism includes a supporting structure forsupporting the half mould tools such that in the open position the halfmould tools are mutually spaced from each other in an extension planeextending substantially parallel to the plane of extension of the sheetand such that in the closed position the half mould tools are mutuallyarranged in contact with each other. The drive mechanism furtherincludes a driver for moving the half mould tools simultaneously fromthe open position to the closed position and vice versa such that thedirection of movement of each of the half mould tools between the openand closed positions comprises a directional component extendingparallel to the sheet extension plane and a directional componentextending perpendicularly to the sheet extension plane.

With such a configuration of the drive mechanism, it is advantageouslypossible to effectively directly mould opening devices of many variousshapes which may include, in particular, portions which protrude andextend in a plane which is parallel to the extension plane of the sheet.Moreover, the particular configuration of the drive mechanism is suchthat the half mould tools mutually arrive and make contact together atthe closed position with a delicate approach so as to provide forminimum wear of the half mould tools. According to a most preferredembodiment, the drive mechanism is configured such that the direction ofmovement of each of the half mould tools between the open and closedpositions tangentially follows a circular path, thereby for minimisingthe space requirements of the opening device moulding apparatus and forminimising wear on the half mould tools.

In accordance with yet another aspect of the invention, there isprovided an opening device moulding apparatus for injection mouldingplastics material opening devices at holes in a packaging materialsheet, including first and second mould tools arrangeable in open andclosed positions respectively spaced apart from and engaging the sheet,wherein in the closed position the sheet extends in a plane which isdistally spaced from the plane of extension of the sheet in the openposition. When the sheet is spaced from its normal extension by themould tools in the closed position, it is put under an added tensionwhich advantageously facilitates the release of the sheet and mouldedopening device from the mould tools as such mould tools move away fromthe closed position to the open position.

The technical characteristics and advantages of the present inventionwill become apparent to those skilled in the art from the followingdetailed description of some preferred embodiments thereof, describedand illustrated in the accompanying drawings only by way ofnon-limitative example, wherein like reference numerals indicate likeparts.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing feeding of a web of packaging sheetmaterial in a packing machine including an opening device mouldingstation in accordance with one preferred aspect of the invention;

FIG. 2 is a perspective view of the lower portion of an opening devicemoulding station in a first preferred embodiment of the invention;

FIG. 3 is a partially sectional side elevation view of the openingdevice moulding station of FIG. 2 in which the mould tools are in anopen position;

FIG. 4a is a partially sectional side elevation view of the openingdevice of FIG. 3 in which the mould tools are in a closed position;

FIG. 4b is an enlarged sectional detail view of the web disposed betweenthe mould tools of FIG. 4a in the closed position forming a mould cavityready for heated thermoplastics injection moulding;

FIG. 6a is a partially sectional side elevation view of the openingdevice of FIG. 5 in which the mould tools are in a closed position; and

FIG. 6b is an enlarged sectional detail view of the web disposed betweenthe mould tools of FIG. 6a in the closed position forming a mould cavityready for heated thermoplastics injection moulding.

BEST MODES FOR CARRYING OUT THE INVENTION

With initial reference to FIG. 1, there is shown an apparatus 2according to the invention, and the reference numeral 18 indicates apackaging machine for forming package containers from a packaging sheetmaterial web 4. It will be understood that the apparatus 2 may be eitherincorporated in the packaging machine or filling machine 18, or locatedupstream of such machine. Web 4 is fed through packaging machine 2 bymeans of an appropriate drive 6 a-e in a feed direction 8. Drive 6 a-eis adapted for intermittently feeding web 4 at an intermittent feedsection 2 a of machine 2, and for continuously feeding web 4 at acontinuous infeed section 2 b and a continuous outfeed section 2 c,arranged respectively upstream and downstream of the intermittent feedsection 2 a with respect to web feed direction 8.

At intermittent feed section 2 a, there are arranged a hole punchingstation 10 for punching holes in web 4, and an opening device mouldingstation 12 for injection moulding thermoplastics material openingdevices at the holes provided on web 4. Drive 6 a-e is adapted forintermittently feeding web 4 through hole punching station 10 such thatweb 4 is appropriately stopped and correctly positioned at hole punchingstation 10 for a time sufficient to punch the holes in web 4, and drive6 a-e is also adapted for intermittently feeding web 4 through openingdevice moulding station 10 such that the holes in web 4 areappropriately stopped and correctly positioned at opening devicemoulding station 10 for a time sufficient to mould opening devices atthe holes punched previously at hole punching station 10.

Drive 6 a-e includes continuous feed rollers 6 b and 6 c arrangedrespectively at continuous infeed section 2 b for unwinding and feedingweb 4 from a reel 14 of packaging material web, and at continuousoutfeed section 2 c for continuously feeding web 4 with opening devices16 moulded thereon to a container forming station 18 for forming andsealing containers from web 4 and filling the containers with product.

Drive 6 a-e further includes at intermittent feed section 2 aintermittent feed rollers 6 a, tensioning rollers 6 d, and an idlerroller 6 e which together mutually cooperate so as to maintain thetension of web 4 at intermittent feed section 2 a substantially constantin a stopped position, so that the hole punching and opening devicemoulding operations may be carried out with sufficient precision.Moreover, the particular arrangement of drive 6 a-e forms an infeedbuffer magazine 20 and an outfeed buffer magazine 22. Infeed buffermagazine 20 includes a changing infeed web length 4 b which extendsbetween tensioning rollers 6 d and continuous feed rollers 6 b and whichmoves vertically along direction 20′ such that infeed web length 4 bchanges in size (as indicated by dashed lines in FIG. 1) toappropriately compensate for the interface between intermittent feedsection 2 a and continuous infeed section 2 b. Similarly, outfeed buffermagazine 22 includes a changing outfeed web length 4 c which extendsbetween intermittent drive rollers 6 a and continuous feed rollers 6 cand which moves vertically in direction 22′ such that outfeed web length4 c changes in size (as indicated by dashed lines in FIG. 1) toappropriately compensate for the interface between intermittent feedsection 2 a and continuous outfeed section 2 c. In this manner thefeeding of web 4 is continuous at roll 14 and container forming station18 while the feeding of web 4 is intermittent at hole punching station10 and opening device moulding station 12.

In FIG. 1, three hole punching stations 10 and three opening devicemoulding stations 12 are shown, such that three holes are formed in web4 and three opening devices are moulded in web 4 for each intermittentstopped position of web 4. The particular number of hole punchingstations 10 and opening device moulding stations 12 may vary accordingto the requirements. Moreover, hole punching stations 10 and openingdevice moulding stations 12 may move relative to one anotherrespectively in directions 10 a and 12 a along the extension of feedingof web 4, so that the holes and opening devices provided on web may berelatively spaced in different positions to allow to form packagingcontainers of different sizes.

Apparatus and methods for feeding web 4, for punching holes in web 4,and for forming and sealing containers from web 4 and filling thecontainers with product, in the manner as described above, are known,and for example are included in the TBA/19-System manufactured by TetraBrik of Modena, Italy.

Opening device moulding station 10 positioned in combination withpackaging machine 2 advantageously provides an efficient and effectivemeans for continuously moulding an opening device on a web fed from aroll and for successively forming, sealing, and filling a packagingcontainer in the same compact line and continuous method. The adhesionof separately formed and supplied opening devices to the web, as iscarried out in conventional apparatus, is eliminated, thereby to providesavings in time and cost related to the separate production, storage,and transport of the separately formed opening devices. While openingdevice moulding station 10 is particularly advantageous for thesereasons, it is envisaged that opening device moulding station 10 mayoperate in many different manners, for example to mould opening deviceson a fed web which is then rolled into a web reel for later use, or forexample to mould opening devices on any type and shape of packagingsheet material such as packaging material blanks or protruding packagingmaterial flaps to mention only a few. Moreover, packaging machine 2 maybe provided in an alternative form, such that web reel 14 is alreadyprovided with prestamped holes so as to allow to eliminate hole punchstation 10, and/or such that the entire drive of web 4 is performedintermittently. Additionally, container forming station 18 may be anyone of a number of forming stations used to form and seal packages ofdifferent sizes and shapes and to fill different products into theformed packages.

FIGS. 2-4b show a first preferred embodiment of opening device mouldingstation 10′. Opening device moulding station 10′ includes a first mouldtool 20 and a second mould tool 22 which are arrangeable relative to web4 in closed positions so as to be in contact respectively with a firstside 24 of web 4 and a second side 26 of web 4 (FIGS. 4a and 4 b), whenweb 4 is in a stopped position at opening device moulding station 10′.First mould tool 20 and second mould tool 22 are also arrangeablerelative to web 4 in open positions so as to be positioned distallyrespectively from first web side 24 and second web side 26 (FIG. 3), soas to allow the intermittent feeding of web 4 infeed direction 8.

In the particular embodiment shown, first mould tool 20 includes asingle inner mould tool 20 which in operates in a fixed position, andsecond mould tool 22 includes a pair of half outer mould tools 22 a and22 b which are driven between the open and closed positions relative toone another, and relative to web 4 and to inner mould tool 20, by adrive mechanism which is described hereinafter. Inner mould tool 20 isarranged for contact with web first side 24 destined to form an innerside of the packaging container formed with web 4, while outer mouldtools 22 a and 22 b are arranged for contact with web second side 26destined to form an outer side of the packaging container formed withweb 4.

With particular reference to FIG. 4b in the closed moulding positions ofinner mould tool 20 and half outer mould tools 22 a and 22 b, a mouldcavity 28 is formed between inner mould tool 20 and half outer mouldtools 22 a and 22 b in which a hold edge 30, of a hole 32 in web 4correctly positioned at opening device moulding station 10′, isaccommodated.

Mould cavity 28 includes in the embodiment shown a portion 28 a forforming a lid portion of the opening device 16, a portion 28 b forforming a base portion of opening device 16 for connection to web 4, anda connecting portion 28 c for forming a reduced thickness tearing edgeof opening device 16 for aiding in releasing the lid portion from thebase portion. The present disclosure relates more in particular to themanner in which opening device is moulded to web 4 at hole edge 30thereof, while opening device 16 may assume any number of differentoverall shapes.

In the embodiment shown, hole edge 30 is circumferential to completelyenclose the hole in web 4, and preferably the entire hole edge 30 isarranged inside base forming portion 28 a of mould cavity 28 prior toinjection, while base forming portion 28 b is also circumferential andhas a dimension sufficient to completely enclose hole edge 30.Preferably, hole edge 30, base forming portion 28 b, and connectingportion 28 c are ovular ring-shaped in a longitudinal cross sectionextending substantially parallel to the extension of web 4, and lidforming portion 28 a is ovular disc-shaped in a longitudinal crosssection extending substantially parallel to the extension of web 4.Moreover, in the closed moulding position a gap 34 is formed betweenupper and lower mould tools 20 and 22 which preferably has a widthdimension smaller than the thickness of packaging web material 4 therebyto compress web 4 inside gap 34 and form a seal sufficient to preventany significant leakage of the heated thermoplastics material outside ofmould cavity 28.

Opening device moulding station 10′ further includes an injectionpassage 36 for injecting heated thermoplastics material into mouldcavity 28. Injection of heated thermoplastics material through injectionpassage 36 may be carried out using any conventional method andapparatus known and available to a skilled person in the art.

Injection passage 36 extends in fixed inner mould tool 20 in theparticular embodiment shown, and in accordance with a preferred aspectof the invention, injection passage 36 is configured such thatthermoplastics material is injected directly into mould cavity 28 at aninjection point 38 of mould cavity 28 which is located distally fromhole edge 30.

By having injection point 38 arranged distally from hole edge 30, theheated thermoplastics material advantageously enters the mould cavity ata position which permits the filling of the mould cavity to be carriedout in an effective and efficient manner. The heated plastics materialwill flow from injection point 38 smoothly and evenly initially distallyfrom hole edge 30 and successively to fill base forming portion 28 b ofmould cavity 28 so that the heated plastics material makes contact withhole edge 30 at the end of the injection step. The times required foreach injection step are minimised in order to increase the efficiency ofthe opening device moulding operation.

Injection point 38 in the particular embodiment is arranged at lidforming portion 28 a of mould cavity 28, in a substantially centralposition with respect to base forming portion 28 b. Such an arrangementallows to fully maximise the efficiency of material flow from injectionpoint 38 symmetrically and evenly initially distally from hole edge 30and successively to fill base forming portion 28 b of mould cavity 28.

Moreover, injection passage 36 extends in inner mould tool 20 in adirection which is substantially perpendicular to the extension of lidforming portion 28 c of mould cavity 28 so as to fully avoid subjectingsurfaces of web 4 to the flow of heated thermoplastics material.

Inner mould tool 20 and half outer mould tools 22 a and 22 b are drivenbetween the open and closed positions relative to one another, andrelative to web 4 and to inner mould tool 20, by a drive mechanism 40.Drive mechanism 40 is coordinated with drive 6 a-e for feeding web 4,with hole punching station, and with the injection of heatedthermoplastics material through injection passage 36, so as to provide acontinuous production of moulded opening devices 16 on web 4.

Drive mechanism 40 includes a supporting structure 42 for supportinghalf outer mould tools 22 a and 22 b such that in the open position halfouter mould tools 22 a and 22 b are mutually spaced from each other inan extension plane extending substantially parallel to the plane ofextension of web 4 (FIG. 3) and such that in the closed position halfouter mould tools 22 a and 22 b are mutually arranged in contact witheach other and with second web side 26 (FIGS. 4a-4 b). Drive mechanism40 also includes a driver 44 for moving half outer mould tools 22 a and22 b from the open position to the closed position and vice versa suchthat the direction of movement of each of half outer mould tools betweenthe open and closed positions includes a directional component extendingparallel to the extension plane of web 4 and a directional componentextending perpendicularly to the extension plane of web 4.

The particular configuration of drive mechanism 40 which moves halfouter mould tools 22 a and 22 b in such directions as they move betweenthe open and closed positions advantageously allow to effectively formopening devices of many various shapes which may include in particularportions which protrude and extend in a plane which is parallel to theextension plane of web 4.

Moreover, the particular configuration of drive mechanism 40 is suchthat outer half mould tools 22 a and 22 b mutually arrive and makecontact together at the closed position with a delicate approach sincethe movement of each of outer half mould tools 22 a and 22 b may includea direction component parallel to the extension plane of web 4 which isminimised while still achieving mutual contact in the closed position.Such a delicate approach of outer half mould tools 22 a and 22 badvantageously provides for minimum wear of outer half mould tools 22 aand 22 b.

In a most preferred embodiment such as that shown in FIGS. 2-4a drivemechanism 40 is configured such that the direction of movement of eachof outer half mould tools 22 a and 22 b between the open and closedpositions tangentially follows a circular path. In this manner, thedirection movement component parallel to the extension plane of web 4 ofouter half mould tools 22 a and 22 b at the approach and release phasesmost near the dosed position may be minimised virtually to zero whilesuch direction movement component parallel to the extension plane of web4 in phases away from the closed position may be rapidly increased, soas to minimize the space requirements of opening device moulding station10′ and so as to minimise wear on outer half mould tools 22 a and 22 b,while still maintaining flexibility with regard to forming openingdevices of different shapes.

Supporting structure 42 includes a fixed support frame having ahorizontal base 46 and arm pairs 48 a-c extending vertically upward frombase 42. Supporting structure further includes lever pairs 50 and 52freely pivoted respectively between lateral arm pairs 48 a and 48 c andouter half mould tools 22 a and 22 b about pivot axes which extendsubstantially parallel to the plane of extension of web 4.

Supporting structure 42 further includes a horizontal slide plate 54having slots 54 a in which bolts 54 b connected to each of outer halfmould tools 22 a and 22 b are slidably accommodated. Slots 54 a extendin slide plate 54 such that each of outer half mould tools 22 a and 22 bare slidably supported on slide plate 54 in a linear direction extendingparallel to web feed direction 8.

Driver 44 includes a fluid-actuated cylinder 55 having a stem slidablyextending through fixed base 46 and connected to slide plate 54 forreciprocatingly moving slide plate 54 in a vertical direction extendingperpendicularly to the extension of web 4.

This particular configuration of drive mechanism 40 causes outer halfmould tools 22 a and 22 b to move between the open and closed positionsalong a circular path centered about the pivot axes respectively oflever pairs 50 and 52 and lateral arms 48 a and 48 c.

The dimensions of outer half mould tools 22 a and 22 b, of lateral arms48 a and 48 c, and of lever pairs 50 and 52 are such that when outerhalf mould tools 22 a and 22 b are arranged in contact in the closedposition, a contact force between the mating surfaces of outer halfmould tools 22 a and 22 b is created sufficient to provide an adequateseal of mould cavity 28 such that heated thermoplastics material willnot leak excessively out of mould cavity 28 at the location of themating surfaces of outer half moulds 22 a and 22 b. According to afurther aspect of the Invention, there is provided an adjustable biasingdevice for adjustably setting the contact force between outer halfmoulds 22 a and 22 b in the closed position.

For this purpose, lateral arms 48 a and 48 c are provided with throughgaps 56 which make lateral arms 48 a and 48 c relatively flexible in adirection parallel to web feed direction 8, and a pair of tension rods58 are interconnected between lateral arms 48 a and 48 c. Tension rods58 are freely slidably disposed in central arms 48 b, and adjustmentnuts 58 a are adjustably screwed at the ends of tension rods 58.

FIG. 4a illustrates the outward flexure of lateral arms 48 a and 48 cwhen outer half mould tools 22 a and 22 b are in the closed matingposition, and adjustment of nuts 58 a will properly select the desiredcontact force between half mould tools 22 a and 22 b in the dosedposition.

The configuration of supporting structure 42 is such that in the closedposition of outer half mould tools 22 a and 22 b (FIG. 4a), the portionof web 4 which is in contact with outer half mould tools 22 a and 22 bextends in a plane which is distally spaced from the normal plane ofextension of web 4 in the open position of outer half mould tools 22 aand 22 b (FIG. 3). In this manner, web 4 in the spaced position from itsnormal extension is put under an added tension which advantageouslyfacilitates the release of web 4 and moulded opening device 16 frommould tools 20 and 22 as such mould tools 20 and 22 move away from theclosed position to the open position.

FIGS. 5-6b show a second preferred embodiment of opening device mouldingstation 10″. Opening device moulding station 10″ includes a first mouldtool 20′ and a second mould tool 22′ which are arrangeable relative toweb 4 in closed positions so as to be in contact respectively with afirst side 24 of web 4 and a second 26 of web 4 (FIGS. 6a and 5 a 6 b),when web 4 is in a stopped position at opening device moulding station10″. First mould tool 20′ and second mould tool 22′ are also arrangeablerelative to web 4 in open positions so as to be positioned distallyrespectively from first web side 24 and second web side 26 (FIG. 5), soas to allow the intermittent feeding of web 4 in feed direction 8. Firstmould tool 20′ includes a single inner mould tool 20′ movable in avertical direction, and second mould tool 22′ includes a pair of lateralouter mould tools 22 a′ and 22 b′ each movable in the vertical and ahorizontal direction. Inner mould tool 20′ and lateral outer mould tools22 a′ and 22 b′ are driven between the open and closed positionsrelative to one another, and relative to web 4, by a drive mechanismwhich is described hereinafter.

With reference to FIG. 6b, in the closed moulding positions of innermould tool 20′ and lateral outer mould tool 22 a′ and 22 b′, a mouldcavity 28′ is formed between inner mould tool 20′ and lateral outermould tools 22 a and 22 b in which hole edge 30 of hole 32 in web 4correctly positioned at opening device moulding station 10″ isaccommodated. Mould cavity 28′ includes a portion 28 a′ for forming alid portion of the opening device 16, a portion 28 b′ for forming a baseportion of opening deice 16 for connection to web 4, and a connectingportion 28 c′ for forming a reduced thickness tearing edge of openingdevice 16 for aiding in releasing the lid portion from the base portion.

The entire hole edge 30 is preferably arranged inside base formingportion 28 a′ prior to injection, while base forming portion 28 b′ iscircumferential and has a dimension sufficient to completely enclosehole edge 30. Preferably, base forming portion 28 b′ and connectingportion 28 c′ are ovular ring-shaped in a longitudinal cross sectionextending substantially parallel to the extension of web 4, and lidforming portion 28 a′ is ovular disc-shaped in a longitudinal crosssection extending substantially parallel to the extension of web 4.Moreover, in the closed moulding position a gap 34′ is formed betweenupper and lower mould tools 20′ and 22′ which preferably has a widthdimension smaller than the thickness of packaging web material 4 therebyto compress web 4 inside gap 34′ and form a seal sufficient to preventany significant leakage of the heated thermoplastics material outside ofmould cavity 28′.

Opening device moulding station 10″ further includes an injectionpassage 36′ for injecting heated thermoplastics material into mouldcavity 28′. Injection passage 36′ extends in a fixed injection head 60which has an upper end portion 60 a forming part of second mould tool22′, as seen in FIG. 6b. Accordingly lateral outer mould tools 22 a′ and22 b′ are movably arrangeable with respect to fixed upper end portion 60a in the closed moulding position, forming mould cavity 28′.

Injection passage 36′ is configured such that thermoplastics material isinjected directly into mould cavity 28′ at an injection point 38′ ofmould cavity 28′ which is located distally from hole edge 30, thereby toachieve the advantageous effects as obtained by the above describedfirst embodiment of opening device moulding station 10′. Injectionpassage 36′ moreover extends in outer mould tool 22′ in a directionwhich is substantially perpendicular to the extension of lid formingportion 28 c′ of mould cavity 28′, distally from surfaces of web 4.

The drive mechanism for driving inner mould tool 20′ and lateral outermould tools 22 a′ and 22 b′ are between the open and closed positionsincludes a movable support frame 62 arranged circumferentially aboutfixed injection head 60 and movable in a vertical direction, and a fixedsupport frame 64 supporting fluid-activated cylinders 66 a′-b and 68having stems 66 a-b′ and 68′ connected respectively to movable supportframe 62 and inner mould tool 20′ for reciprocatingly moving theseelements in the vertical direction. The drive mechanism further includesfluid-activated cylinders 70 a and 70 b having stems 70 a′ and 70 b′connected respectively to lateral outer mould tools 22 a′ and 22 b′ forreciprocatingly moving these elements in the horizontal direction.

The actuation of cylinders 66 a-b, 68, and 70 a-b is coordinated withdrive 6 a-e for feeding web 4, with hole punching station 10, and withthe injection of heated thermoplastics material through injectionpassage 36′, so as to provide a continuous production of moulded openingdevices 16 on web 4.

What is claimed is:
 1. An opening device moulding apparatus forinjection moulding plastics material opening devices at holes in apackaging material sheet, comprising: at least one first mould toolarrangeable in a closed position so as to be in contact with a firstside of the sheet positioned at said opening device moulding station andarrangeable in an open position so as to be positioned distally from thefirst side of the sheet positioned at said opening device mouldingstation; at least one second mould tool arrangeable in a closed positionso as to be in contact with a second side of the sheet positioned atsaid opening device moulding station and arrangeable in an open positionso as to be positioned distally from the second side of the sheetpositioned at said opening device moulding station; wherein in the openpositions said mould tools are mutually spaced from each other in anextension plane; wherein in the closed positions of said first andsecond mould tools a mould cavity is formed between said first andsecond mould tools for at least partially accommodating a hole edge inthe sheet positioned at said opening device moulding station; aninjection passage for injecting heated thermoplastics material into saidmould cavity, wherein said injection passage extends in at least one ofsaid first and second mould tools such that the thermoplastics materialis injected directly into the mould cavity at an injection point of themould cavity which is located distally from said hole edge accommodatedin said mould cavity; and a drive mechanism for selectively moving saidfirst mould tool and said second mould tool between said open and dosedpositions, at least one of said first and second mould tools including apair of half mould tools, wherein said drive mechanism is configuredsuch that the direction of movement of each of said half mould toolsbetween said open and closed positions have a directional componentextending substantially parallel to the extension plane and adirectional component extending substantially perpendicularly to theextension plane.
 2. The apparatus of claim 1 wherein said mould cavityhas a base portion for accommodating said hole edge in the closedpositions of said first and second mould tools and for forming a base ofsaid moulded opening device, and a lid portion for forming a lid of themoulded opening device.
 3. The apparatus of claim 1 wherein saidinjection point of the mould cavity is arranged at said lid portion in asubstantially central position with respect to said base portion.
 4. Theapparatus of claim 3 wherein said injection passage extendssubstantially perpendicularly to the extension of said lid portion ofsaid mould cavity.
 5. The apparatus of claim 1, wherein said drivemechanism comprises: a supporting structure for supporting said halfmould tools such that in the open position said half mould tools aremutually spaced from each other in an extension plane extendingsubstantially parallel to the plane of extension of the sheet and suchthat in the closed position said half mould tools are mutually arrangedin contact with each other and with said second side of the sheet; and adriver for moving said half mould tools simultaneously from the openposition to the closed position and vice versa.
 6. The apparatus ofclaim 1 wherein said drive mechanism is configured such that thedirection of movement of each of said half mould tools between said openand closed positions tangentially follows a circular path.
 7. Theapparatus of claim 5 wherein in said closed position said sheet extendsin a plane which is distally spaced from the plane of extension of saidsheet in said open position.
 8. The apparatus of claim 5 furthercomprising an adjustable biasing device for adjustably setting a contactforce between said half mould tools in said closed position.
 9. A methodfor direct injection moulding of a plastics material opening device to ahole which is disposed in a sheet of packaging material and which has ahole edge, comprising the steps of: moving at least one first mould toolfrom an open position to a closed position in contact with a first sideof the packaging sheet material and moving at least one second mouldtool from an open position to a closed position in contact with a secondside of the packaging sheet material, thereby forming a mould cavitydefined between said first and second mould tools in a manner such thatat least a portion of said hole edge is arranged inside said mouldcavity, wherein in the open positions said mould tools are mutuallyspaced from each other in an extension plane; wherein at least one ofsaid first and second mould tools defines a pair of half mould tools,and comprising moving said half mould tools along a direction ofmovement of each of said half mould tools between said open and closedpositions in a direction of movement having a directional componentextending substantially parallel to the extension plane and adirectional component extending substantially perpendicularly to theextension plane; and injecting plastics material into said mould cavityso as to form the plastics material opening device wherein the plasticsmaterial is injected directly into the mould cavity at an injectionpoint of the mould cavity which is located distally from said portion ofthe hole edge.
 10. The method of claim 9 including arranging the firstand second mould tools so as to form a mould cavity having a baseportion for forming a base of the opening device and a lid portion forforming a lid of the opening device in a manner such that all of saidhole edge is arranged inside said base portion of said mould cavity. 11.The method of claim 10 including injecting plastics material at aninjection point arranged at the lid portion of the mould cavity in asubstantially central position with respect to said hole edge.
 12. Themethod of claim 11 including injecting plastics material through ainjection channel which is disposed in one of said first and secondmould tools and which extends substantially perpendicularly to theextension of said lid portion of said mould cavity.